1. Introduction to Minerals
Potassium Fedspar
Quartz

2. What is a mineral??? Naturally ocurring Inorganic Crystalline solid
Defined chemical composition

3. What is a mineral??? Naturally ocurring Inorganic Crystalline solid
Defined chemical composition
-Building blocks of rocks, i.e.
Rocks are made of minerals

4. Physical properties of minerals
Crystal Form
-Minerals have different shapes because of the special arrangement of atoms within them.

5. Physical properties of minerals
Crystal Form
-Minerals have different shapes because of the special arrangement of atoms within them.
-Size increases with time of crystallization.

6. Some minerals exhibit better crystalline form

7. Physical properties of minerals (continued)
Luster
Appearance of a mineral in reflected light
Two basic categories
Metallic
Non-Metallic

8. Physical properties of minerals (continued)
Luster
Appearance of a mineral in reflected light
Two basic categories
Metallic
Non-Metallic
Other terms: vitreous, silky, earthy

9. Galena is a lead sulfide (PbS) that displays metallic luster

10. Physical properties of minerals (continued)
Color
Generally an unreliable diagnostic property
Highly variable for a given mineral due to slight changes in mineral chemistry

11. Physical properties of minerals (continued)
Color
Generally an unreliable diagnostic property
Highly variable for a given mineral due to slight changes in mineral chemistry
Exotic colorations of some minerals produce gemstones

12. Physical properties of minerals (continued)
Color
Generally an unreliable diagnostic property
Highly variable for a given mineral due to slight changes in mineral chemistry
Exotic colorations of some minerals produce gemstones

13. Physical properties of minerals (continued)
Streak
Color of a mineral in its powdered form
Helpful in distinguishing different forms of the same mineral

14. Physical properties of minerals (continued)
Streak
Color of a mineral in its powdered form
Helpful in distinguishing different forms of the same mineral
Hardness
Resistance of a mineral to abrasion or scratching
All minerals are compared to a standard scale called the Mohs scale of hardness

15. Relative hardness…
—Rubies & Sapphires
—Our teeth!
—TUMS!
micas

16. Streaking a mineral…
Streak
Streak color
unglazed ceramic

17. Physical properties of minerals (continued)
Cleavage
Minerals will break in a certain direction where the bonds between atoms are not strong.
Produces flat, shiny surfaces

18. Physical properties of minerals (continued)
Cleavage
Minerals will break in a certain direction where the bonds between atoms are not strong.
Produces flat, shiny surfaces
Described by:
Number of planes
Angles between adjacent planes

19. Three examples of perfect cleavage – fluorite, halite, & calcite

20. Some more cleavage examples…
Micas—one plane of perfect cleavage, can peel off sheets!

21. Physical properties of minerals (continued)
Fracture
-Minerals that do not have cleavage will fracture when they are broken.
-If the fracture has a smooth, curved surface it is called a conchoidal fracture.

22. Conchoidal fracture examples…

23. Physical properties of minerals (continued)
Other properties
Magnetism
Reaction to hydrochloric acid
Malleability
Double refraction
Taste
Smell

24. Acid Test
Cool….

25. To Summarize…
-Minerals are crystalline, inorganic, naturally occurring solids
-Rock = composed of minerals
-Minerals distinguished by physical properties:
-Form
-Luster
-Color
-Streak
-Hardness
-Cleavage/Fracture